ENERGY DEMANDS ON WATER RESOURCES REPORT TO CONGRESS ON THE INTERDEPENDENCY OF ENERGY AND WATER U.S. DEPARTMENT OF ENERGY DECEMBER 2006 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 1
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PREFACE This report has been prepared in response to a letter to the Secretary of Energy from the chairmen and ranking members of the House and Senate Subcommittees on Energy and Water Development Appropriations, dated December 9, 2004, wherein they asked for: a report to Congress on the interdependency of energy and water focusing on threats to national energy production resulting from limited water supplies, utilizing where possible the multi-laboratory Energy-Water Nexus Committee. The report presents background information on the connections between energy and water, identifies concerns regarding water demands of energy production, and discusses science and technologies to address water use and management in the context of energy production and use. 3 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 3
CONTENTS Executive Summary... 9 Chapter I. Energy and Water Are Essential, Interdependent Resources... 13 Chapter II. Supplying Energy Requires Water and Impacts Water Quality... 17 Water Use for Thermoelectric Power Generation... 18 Water Use for Hydroelectric Power Generation... 19 Water Use for Energy Extraction and Fuel Production... 20 Water Produced During Energy Extraction... 21 Energy Impacts on Water Quality... 21 Chapter III. Supplying Water Requires Energy... 25 Supply and Conveyance... 25 Treatment and Distribution... 26 End Use of Water... 26 Future Energy Demand for Water Supply and Treatment... 27 Chapter IV. Water Shortages and Impacts on Energy Infrastructure... 29 Water Management Challenges... 31 Surface Water Concerns... 32 Groundwater Concerns... 32 Potential Impact of Future Power Generation on Water Supplies... 33 Chapter V. Opportunities to Secure America s Energy and Water Future... 37 Addressing Future Water Needs in the Power Sector... 37 Addressing Water Needs in the Emerging Fuel Sector... 43 Addressing Future U.S. Water Needs... 45 Chapter VI. Addressing Critical Energy-Water Challenges: Bridging the Gaps... 49 Collaboration on Critical Resource Planning... 49 Science and System-Based Natural Resource Policies and Regulations... 49 Energy-Water Infrastructure Synergies... 49 Bridging the Gaps: Direction and Implementation... 50 Appendix A: Water Use in Energy Extraction, Processing, Storage, and Transportation... 53 Appendix B: Water Use in Electrical Power Generation... 63 References and Bibliography... 71 4 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 4
Figures Figure I-1. Examples of Interrelationships Between Water and Energy...13 Figure I-2. Water Shortages and Population Growth....15 Figure II-1. Estimated Freshwater Withdrawals by Sector, 2000...18 Figure II-2. Open-Loop Cooling System...18 Figure II-3. Closed-Loop Cooling System...19 Figure II-4. Estimated Freshwater Consumption by Sector, 1995...19 Figure II-5. U.S. Hydropower Production...19 Figure II-6. Forecast for Produced Water (Wp) from Oil and Gas Extraction...22 Figure III-1. Percent of U.S. Electricity Consumption by Sector...25 Figure III-2. Per Capita Energy Use for Water Supply and Wastewater Treatment in 2000 and Projected for 2050....26 Figure IV-1. Survey of Likely Water Shortages over the Next Decade under Average Conditions...29 Figure IV-2. Examples of Energy-Water Conflicts...30 Figure IV-3. Trends in Total Freshwater Withdrawals, 1950 2000...31 Figure IV-4. Comparison of Regional Thermoelectric Generation Capacity by North American Electric Reliability Council Region, 1995 2025...34 Figure IV-5. Projected Steam-Electric Generation Capacity by Type Projected from EIA Reference Case...35 Figure IV-6. Range of Projected Daily Freshwater Withdrawal for Thermoelectric Power Generation...36 Figure IV-7. Range of Projected Freshwater Consumption for Thermoelectric Power Generation...36 Figure V-1. Water Withdrawal for Power Generation...39 Figure V-2. Water Consumption for Power Generation...39 Figure V-3. Peak Reduction from Combined Use of Solar Energy and Demand Management in a Residential Application...42 Figure V-4. Water Consumption Per-Unit-Energy and Current Water Use for Fuel Extraction and Processing...44 Figure V-5. Degraded Water Resources of the U.S...46 Figure V-6. Energy Requirements for Water Desalination...47 Figure V-7. U.S. Oil and Gas Resources....48 Tables Table II-1. Connections Between the Energy Sector and Water Availability and Quality...17 Table III-1. Energy Requirements for Water Supply and Treatment in California...25 Table IV-1. Examples of Declining Groundwater Levels...33 Table V-1. Water Intensity for Various Power Generation Technologies...38 5 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 5
Acronyms API AwwaRF bbl boe CEC DOE EERE EIA EOR EPRI EST FE ft FY gal GAO GW IGCC kw kwh LNG MGD MMbbls MMBtu MTBE MW MWh MWh e MWh t NETL American Petroleum Institute Awwa Research Foundation barrel barrel of oil equivalent California Energy Commission U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy Energy Information Administration, U.S. Department of Energy Enhanced Oil Recovery Electric Power Research Institute Eastern Standard Time Office of Fossil Energy, U.S. Department of Energy feet fiscal year gallons General Accounting Office gigawatt Integrated Gasification Combined Cycle kilowatt kilowatt-hour Liquefied Natural Gas million gallons per day million barrels Million British Thermal Units methyl tertiary-butyl ether megawatt Megawatt-hour Megawatt-hour of electric energy Megawatt-hour of thermal energy National Energy Technology Laboratory 6 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 6
NCPA NGCC PV PNM psi RFA SWAQ TVA USDA USGS W p WW yr Northern California Power Authority Natural Gas Combined Cycle Photovoltaic Public Service Company of New Mexico pound per square inch Renewable Fuels Association Subcommittee on Water Availability and Quality Tennessee Valley Authority United States Department of Agriculture United States Geological Survey water produced wastewater year 7 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 7
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Executive Summary For the past century, America has invested significant research, development, and construction funding to develop both fresh surface-water and groundwater resources. The result is a water infrastructure that allows us to harness the vast resources of the country s rivers and watersheds, control floods, and store water during droughts to provide reliable supplies of freshwater for agricultural, industrial, domestic, and energy uses. During this same period, the U.S. developed extensive natural resources such as coal, oil, natural gas, and uranium and created an infrastructure to process and transport these resources in an efficient and cost-effective manner to consumers. These two achievements have helped stimulate unprecedented economic growth and development. However, as population has increased, demand for energy and water has grown. Competing demands for water supply are affecting the value and availability of the resource. Operation of some energy facilities has been curtailed due to water concerns, and siting and operation of new energy facilities must take into account the value of water resources. U.S. efforts to replace imported energy supplies with nonconventional domestic energy sources have the potential to further increase demand for water. responds to a Congressional directive within a letter to the Secretary of Energy from the chairmen and ranking members of the House and Senate Subcommittees on Energy and Water Development Appropriations, dated December 9, 2004, wherein they asked for a report on energy and water interdependencies, focusing on threats to national energy production that might result from limited water supplies. This report draws on the work of the multilaboratory Energy-Water Nexus committee as well as reports and papers from researchers in other federal agencies and elsewhere. ENERGY AND WATER INTER- DEPENDENCIES Water is an integral element of energy resource development and utilization. It is used in energy-resource extraction, refining and processing, and transportation. Water is also an integral part of electric-power generation. It is used directly in hydroelectric generation and is also used extensively for cooling and emissions scrubbing in thermoelectric generation. For example, in calendar year 2000, thermoelectric power generation accounted for 39 percent of all freshwater withdrawals in the U.S., roughly equivalent to water withdrawals for irrigated agriculture (withdrawals are water diverted or withdrawn from a surface-water or groundwater source) (Hutson et al., 2004). Water withdrawal statistics for thermoelectric power are dominated by power plants that return virtually all the withdrawn water to the source. While this water is returned at a higher temperature and with other changes in quality, it becomes available for further use. Many power plants, including most of those built since 1980, withdraw much less water but consume most of what they withdraw by evaporative cooling. In 1995, agriculture accounted for 84 percent of total freshwater consumption. Thermoelectric power accounted for 3.3 percent of total freshwater consumption (3.3 billion gallons per day) and represented over 20 percent of nonagricultural water consumption (Solley et al., 1998). 9 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 9
The Energy Information Administration (EIA) projects, assuming the latest Census Bureau projections in its reference case, the U.S. population to grow by about 70 million in the next 25 years and electricity demand to grow by approximately 50 percent (EIA, 2006). The EIA reference case is a projection which assumes that current laws, regulations, policies, technological progress and consumer preferences continue through the projection period as they have in the past. The EIA reference case provides a useful baseline against which possible changes to these assumptions can be evaluated. Much of this growth is expected to occur in the Southeast, Southwest, and Far West, where water is already in limited supply. In a business-as-usual scenario, consumption of water in the electric sector could grow substantially, though increased demand for water would provide an incentive for technologies that reduce water use, thus dampening the increase in water use. Technologies are available that can reduce water use in the electric sector, including alternative cooling for thermoelectric power plants, wind power, and solar photovoltaics, but cost and economics, among other factors, have limited deployment of these technologies. In contrast, water use in the extraction and processing of transportation fuels is relatively small. However, as the U.S. seeks to replace imported petroleum and natural gas with fuels from domestic sources, such as biofuels, synfuel from coal, hydrogen, and possibly oil shale, the demand for water to produce energy fuels could grow significantly. Growth in energy demand occurs when freshwater resources and overall freshwater availability become strained from limitations on supply and increasing domestic, agricultural, and environmental demands. Few new reservoirs have been built since 1980, and fresh surface-water withdrawals 10 have leveled off at about 260 billion gallons per day. Many regions depend on groundwater to meet increasing water demands, but declining groundwater tables could severely limit future water availability. Some regions have seen groundwater levels drop as much as 300 to 900 feet over the past 50 years because of the pumping of water from aquifers faster than the natural rate of recharge. A 2003 General Accounting Office study showed that most state water managers expect either local or regional water shortages within the next 10 years under average climate conditions (GAO, 2003). Under drought conditions, even more severe water shortages are expected. Depending on the water quality needs for particular applications, freshwater supplies can be augmented with degraded or brackish water. Water quantities available for use are dependent on the water qualities needed for each use. Increased use of brackish or degraded water may be required in some areas if water users can accept the quality limitations or can afford the cost of energy and infrastructure for water treatment. ENERGY DEMANDS ON WATER RESOURCES These trends in energy use, water availability, and water demand suggest that the U.S. will continue to face issues related to the development, utilization, and management of the critical resources of water and energy. Increasing population will increase demand for water for direct use as well as for energy and agriculture. Historically, water withdrawals for domestic supplies have grown at about the same rate as the population, though recent trends show that rate growing about half the rate of population growth because of the implementation of water conservation measures in many regions (Hutson et al., 2004; GAO, 2003). If new power plants continue to be built with evaporative cooling, consumption of water for electrical energy production could more than double by 2030 from 3.3 billion gallons per day in CA Water Plan Update 2009 Vol. 4 Reference Guide Page 10
1995 to 7.3 billion gallons per day (Hoffmann et al., 2004). Consumption by the electric sector alone could equal the entire country s 1995 domestic water consumption. Consumption of water for extraction and production of transportation fuels from domestic sources also has the potential to grow substantially. Meanwhile, climate concerns and declines in groundwater levels suggest that less freshwater, not more, may be available in the future. Therefore, the U.S. should carefully consider energy and water development and management so that each resource is used according to its full value. Since new technologies can reduce water use, there will be a great incentive for their development by the public and private sectors. Given current constraints, many areas of the country will have to meet their energy and water needs by properly valuing each resource, rather than following the current U.S. path of largely managing water and energy separately while making small improvements in freshwater supply and small changes in energy and water-use efficiency. FEDERAL ROLES IN MEETING ENERGY-WATER CHALLENGES While regulation of electric and water utilities and resource allocations is primarily a state or local responsibility, federal agencies such as the Bureau of Reclamation manage some of our largest energy and water resources in cooperation with state and local entities. Expansion of this cooperation could improve the country s ability to address these energy challenges. Collaboration on Resource Planning Collaboration on energy and water resource planning is needed among federal, regional, and state agencies as well as with industry and other stakeholders. In most regions, energy planning and water planning are done separately. The lack of integrated energy and water planning and management has already impacted energy production in many basins and regions across the country. For example, in three of the fastest growing regions in the country, the Southeast, Southwest, and the Northwest, new power plants have been opposed because of potential negative impacts on water supplies (Tucson Citizen, 2002; Reno-Gazette Journal, 2005; U.S. Water News Online, 2002 and 2003; Curlee, 2003). Also, recent droughts and emerging limitations of water resources have many states, including Texas, South Dakota, Wisconsin, and Tennessee, scrambling to develop water use priorities for different water use sectors (Clean Air Task Force, 2004a; Milwaukee Journal Sentinel, 2005; GAO, 2003; Curlee, 2003; Hoffman, 2004; U.S. Water News Online, 2003). Also see Chapter IV, Figure IV-2 for other examples. Mechanisms, such as regional natural resources planning groups, are needed to foster collaboration between stakeholders and regional and state water and energy planning, management, and regulatory groups and agencies. These collaborative efforts are needed to ensure proper evaluation and valuation of water resources for all needs, including energy development and generation. Science and System-Based Natural Resource Policies and Regulations Often, polices or regulations developed to support or enhance one area, such as increasing domestic energy supplies through enhanced oil recovery (EOR), could have unintended negative impacts on regional or national freshwater availability or water quality. System-level evaluations by stakeholders and government agencies can be used to assess the impact of current or proposed natural resource policies and regulations and improve future energy development and water availability. 11 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 11
Energy Water Infrastructure Synergies When the energy infrastructure is evaluated in a system context, significant improvements in energy and water conservation can often be realized through implementation of innovative processes or technologies, colocation of energy and water facilities, or improvements to energy and water infrastructures. Past investments in the water infrastructure by creating dams and surfacewater reservoirs in the U.S. over the past 80 years have significantly improved the availability of water for some applications and decreased its availability for other applications. There will continue to be competition for water resources between different users, and ways to reduce these conflicts through coordinated infrastructure development would be beneficial. ADDRESSING THE CHALLENGES Available surface water supplies have not increased in 20 years, and groundwater tables and supplies are dropping at an alarming rate. New ecological water demands and changing climate could reduce available freshwater supplies even more. At the same time, populations continue to grow and move to areas with already limited water supplies. The growing competition of water availability for energy production and electric-power generation has already been documented in many river basins. Possible changes in energy strategies in the electricity or transportation sectors could put an even larger burden on freshwater supplies and consumption. As a result, the value of water may increase, impacting energy costs and providing incentives for developing and implementing approaches to decrease the water intensity of the energy sector. While there have been significant improvements in water-use and energy-use efficiency and conservation, market and political (e.g., state) forces will continue to expand these efforts to meet the growing energy and water demands. 12 Two reports currently under development, the Subcommittee on Water Availability and Quality (SWAQ) strategic plan for federal science and technology to support water availability and quality, and the Department of Energy's Energy-Water Science and Technology Research Roadmap, will provide insight into emerging energy-water challenges. The two efforts are independent but closely related. The SWAQ was established in 2003 under the National Science and Technology Council Committee on Environment and Natural Resources and is comprised of the 25 federal agencies with responsibility for the science and technology of water availability and quality. Their role is to coordinate a multiyear plan to improve research to understand the processes that control water availability and quality, and to collect and make available the data needed to ensure an adequate water supply for the Nation s future. Many of the energy and water interdependencies and challenges identified in this report to Congress fall within the SWAQ charter and should be considered by the SWAQ. Congress provided funding in fiscal year (FY) 2005 for the U.S. Department of Energy (DOE) to initiate an Energy-Water Science and Technology Research Roadmap. The Roadmap process started in August 2005 and will be completed by the end of 2006. By the end of 2006, the combined efforts of the SWAQ and the Energy-Water Science and Technology Research Roadmap efforts should provide a detailed understanding of the major energy-water interdependencies, issues, needs, and challenges across the country. The results and conclusions from these efforts should be considered to help guide programs and approaches to address emerging energy and water challenges. CA Water Plan Update 2009 Vol. 4 Reference Guide Page 12
Chapter I. Energy and Water Are Essential, Interdependent Resources A strategic goal of the United States Department of Energy is Promoting America s energy security through reliable, clean, and affordable energy (USDOE, 2006a). The availability of adequate water supplies has an impact on the availability of energy, and energy production and generation activities affect the availability and quality of water. In today s economies, energy and water are linked, as illustrated in Figure I-1. Each requires the other. As these two resources see increasing demand and growing limitations on supply, energy and water must begin to be managed together to maintain reliable energy and water supplies. The interaction of energy and water supplies and infrastructures is becoming clearer. Low water levels from drought and competing uses have limited the ability of power plants to generate power (Columbia Basin News, 2006; also see Chapter IV, Figure IV- 2). Additionally, water levels in aquifers in many regions of the U.S. have declined significantly, increasing energy requirements for pumping, and, in some cases, leading to ground subsidence issues. Figure I-1. Examples of Interrelationships Between Water and Energy 13 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 13
Lack of water for thermoelectric power plant cooling and for hydropower can constrain generation and has the potential to increase demand for technologies that reduce the water intensity of the energy sector. At the same time, demand for energy continues to grow. In its reference case, the Energy Information Administration projects that demand for energy supplies from 2003 to 2030 will grow as follows: petroleum, 38 percent; natural gas, 20 percent; coal, 54 percent; nuclear power, 14 percent; and renewable energy, 58 percent. Demand for electricity from all sources is projected to increase by 53 percent (EIA, 2006). Unfortunately, freshwater withdrawals already exceed precipitation in many areas across the country, as illustrated in Figure I-2 (composed from information from EPRI, 2003a; Solley et al., 1998; and Campbell, 1997). The figure shows the ratio of total freshwater withdrawals in all counties in the U.S. divided by available precipitation (precipitation minus evapotranspiration) shown as a percentage. The figure provides an indication of the areas where current water demands are being met with significant groundwater pumping or transport of surface water from other locales. The shortfalls are most dramatic in the Southwest, in the high plains, in California, and in Florida. Population growth in these regions between 2000 and 2025 is estimated to be 30 to 50 percent (Campbell, 1997). This additional population will place an increased demand on water and energy, given current trends in energy and water use efficiency. The challenges are not limited to these regions, however. For example, the data presented from EPRI show that nearly the entire western shoreline of Lake Michigan has water demand above available precipitation (EPRI, 2003a). Groundwater levels along the southwestern shores of Lake Michigan have declined hundreds of feet since predevelopment and by 1980 had reached maximum withdrawals of up to 900 feet near Chicago (Bartolino and Cunningham, 2003; Granneman et al., 2000). While subsequent relocation of withdrawals has caused groundwater levels near Chicago to rise several hundred feet (Granneman et al., 2000), levels are declining as much as 17 feet per year in some locations (Michigan Land Use Institute, 2003). 14 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 14
Topic: Energy +37% +20% +68% +81% +29% % +10% +36% Projected Population Growth From Campbell, 1997 Source: Solley, 1998; EPRI 2003, A Survey of Water Use Figure I-2. Water Shortages and Population Growth (Water shortage is defined as total freshwater withdrawal divided by available precipitation. Water withdrawal data are taken from Solley et al., 1998; ratios shown are taken from EPRI, 2003a; and projected population growth is taken from Campbell, 1997.) CA Water Plan Update 2009 15 Vol. 4 Reference Guide Page 15
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Chapter II. Supplying Energy Requires Water and Impacts Water Quality Water is used throughout the energy sector, including in resource extraction, refining and processing, electric power generation, storage, and transport. The energy sector also can impact water quality via waste streams, runoff from mining operations, produced water from oil and gas extraction, and air emissions that may affect downwind watersheds. Examples of interactions, both large and small, are shown in Table II-1. Many energy facilities, such as power plants, mines, and refineries, are very large and can have a significant impact on local water supplies and water quality. For example, water withdrawals for thermoelectric power generation alone are comparable to water withdrawals for irrigation. Each represents about 40 percent of the national water withdrawals (water that is diverted or withdrawn from a surface-water or groundwater source), as shown in Figure II-1 (Hutson et al., 2004). However, of the 132 billion gallons per day of freshwater withdrawn for thermoelectric power plants in 1995, all but about 3.3 billion gallons per day (3 percent) was returned to the source. While this water was returned at a higher temperature and with other changes in water quality, it was available for further use. In contrast, of the 134 billion gallons per day withdrawn for irrigation in 1995, 81 billion gallons per day were consumed by evaporation and transpiration (60 percent), and another 25 billion gallons per day (19 percent) were reported as lost in conveyance (but may have percolated to a groundwater source and been available for reuse) (Solley et al., 1998). Table II-1. Connections Between the Energy Sector and Water Availability and Quality Energy Connection to Element Water Quantity Energy Extraction and Production Oil and Gas Water for drilling, Exploration completion, and Oil and Gas Production Coal and Uranium Mining fracturing Large volume of produced, impaired water* Mining operations can generate large quantities of water Electric Power Generation Thermoelectric (fossil, biomass, nuclear) Surface water and groundwater for cooling** and scrubbing Connection to Water Quality Impact on shallow groundwater quality Produced water can impact surface and groundwater Tailings and drainage can impact surface water and ground-water Thermal and air emissions impact surface waters and ecology Hydroelectric Reservoirs lose large Can impact water quantities to temperatures, evaporation quality, ecology Solar PV and None during operation; minimal water use Wind for panel and blade washing *Impaired water may be saline or contain contaminants Energy Connection to Element Water Quantity Refining and Processing Traditional Water needed to Oil and Gas refine oil and gas Refining Biofuels and Water for growing Ethanol Synfuels and Hydrogen and refining Water for synthesis or steam reforming Energy Transportation and Storage Energy Water for Pipelines hydrostatic testing Coal Slurry Water for slurry Pipelines transport; water not Barge Transport of Energy Oil and Gas Storage Caverns returned River flows and stages impact fuel delivery Slurry mining of caverns requires large quantities of water **Includes solar and geothermal steam-electric plants Connection to Water Quality End use can impact water quality Refinery wastewater treatment Wastewater treatment Wastewater requires treatment Final water is poor quality; requires treatment Spills or accidents can impact water quality Slurry disposal impacts water quality and ecology 17 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 17
U.S. Freshwater Withdrawals, 345 Bgal/day Public Supply, 13% Industrial, 5% Mining, 1% Thermoelectric, 39% Irrigation, 40% Domestic, 1% Aquaculture, 1% Livestock, 1% Figure II-1. Estimated Freshwater Withdrawals by Sector, 2000 (Hutson et al., 2004) An overview of the most significant current uses of water in the energy sector is given in this chapter. A more detailed overview of water use in the energy sector is provided in Appendices A and B. WATER USE FOR THERMO- ELECTRIC POWER GENERATION Thermoelectric generating technologies that use steam to drive a turbine generator require cooling to condense the steam at the turbine exhaust. These plants can receive heat from a variety of sources, including coal, nuclear, natural gas, oil, biomass (e.g., wood and crop waste), concentrated solar energy, and geothermal energy. The amount of freshwater required is significant: 59 billion gallons of seawater and 136 billion gallons of freshwater per day (Hutson et al., 2004). Prior to 1970, most thermoelectric power plants were built adjacent to surface waters in the vicinity of large population centers (EIA, 2004b). These older plants commonly use open-loop cooling. They withdraw water for cooling and discharge the heated water back to the source, as shown in Figure II-2. The discharged water can lead to some enhanced evaporative loss to the atmosphere. EPRI estimates these losses to be about 1 percent (EPRI, 2002a). This estimate is reflected in water consumption data for open-loop cooling reported in Chapter V. About 31 percent of current U.S. generating capacity is composed of thermoelectric generating stations using open-loop cooling. While these plants do not consume large volumes of water, the availability of large volumes of water is critical to plant operation. Additionally, the intake and discharge of large volumes of water by these plants have potential environmental consequences. Aquatic life can be adversely affected by impingement on intake screens or entrainment in the cooling water and by the discharge of warm water back to the source. Enactment of the Federal Water Pollution Control Act in 1972 placed restrictions on the impact of open-loop cooling on the environment. In addition, demand for electric power has been high in areas where surface waters are not plentiful, such as the Southwest. Only about ten steam-electric plants have been built with open-loop cooling since 1980 (EIA, 2004b). Nevertheless, existing open-loop cooling systems may have several decades of service life and therefore continue to represent a significant demand for water, though an increased value of water could provide an incentive for cooling improvements that need less water. Condensate Steam River Condenser Figure II-2. Open-Loop Cooling System 18 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 18
Most thermoelectric plants installed since the mid-1970s are cooled by evaporation of the cooling water (EIA, 2004b). As shown in Figure II-3, water is pumped in a closed loop through a cooling tower or a cooling pond. These systems withdraw less than 5 percent of the water withdrawn by openloop systems, but most of the water withdrawn is lost to evaporation. Condensate Steam Condenser Pump Freshwater Supply Water Vapor Cooling Tower Blowdown Figure II-3. Closed-Loop Cooling System Total freshwater consumption for the thermoelectric power sector was 3.3 billion gallons per day in 1995 (Solley et al., 1998). While that was only 3.3 percent of total U.S. water consumption (which amounts to about 100 billion gallons/day), it was nearly 20 percent of nonagricultural consumption, as shown in Figure II-4. U.S. Freshwater Consumption, 100 Bgal/day Irrigation 80.6% Livestock 3.3% Industrial 3.3% Domestic 7.1% Mining 1.2% Commercial 1.2% Thermoelectric 3.3% Figure II-4. Estimated Freshwater Consumption by Sector, 1995 (Solley et al., 1998) WATER USE FOR HYDROELECTRIC POWER GENERATION Hydroelectric power is an important component of U.S. electricity generation. Hydropower supplied from 5.8 percent to 10.2 percent of generated power between 1990 and 2003 (EIA, 2005). As shown in Figure II-5, hydroelectric power production varies greatly with the amount of water available, depending upon weather patterns and local hydrology, as well as on competing water uses, such as flood control, water supply, recreation, and in-stream flow needs (e.g., navigation and the aquatic environment). In addition to being a major source of baseload generating capacity in some regions, hydroelectric power plays an important role in stabilizing the electrical transmission grid and in meeting peak loads, reserve requirements, and other ancillary electrical energy needs because it can respond very quickly to changing demand. Billion Kilowatthours 400 350 300 250 200 150 100 50 Recent range (±35%) happened with essentially no change in capacity 0 1940 1950 1960 1970 1980 1990 2000 2010 Year Figure II-5. U.S. Hydropower Production (EIA, 2005) Hydroelectric plant design and operation is highly diverse. Projects vary from large, multipurpose storage reservoirs to run-of-river projects that have little or no active water storage. Approximately half the U.S. hydropower capacity is federally owned and operated; the other half is nonfederal projects that are regulated by the Federal Energy Regulatory Commission. 19 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 19
There are more than ten times more nonfederal hydropower projects in the U.S. than federal projects. Water flow through hydroelectric turbines averages 3,160 billion gallons/day (Solley et al., 1998) or nearly ten times the withdrawals of water from rivers. The United States Geological Survey (USGS) does not report it as withdrawn water because it remains in the river and, in fact, can be used multiple times by successive dams. However, reservoir operation can shift water releases in time relative to natural flows. When hydropower projects involve large storage reservoirs, evaporation of water from those reservoirs can be a significant consumptive use. With an average loss for U.S. hydroelectric reservoirs of 4,500 gal/mwh (Gleick, 1994) and annual generation of approximately 300 million MWh (EIA 2005), total losses are estimated at 3.8 billion gallons per day. However, the water storage in hydropower reservoirs usually has multiple purposes; thus, hydroelectric power is not the only cause of these evaporative losses. WATER USE FOR ENERGY EXTRACTION AND FUEL PRODUCTION Water consumption for energy extraction and fuel production is included by the USGS under the industrial/mining sector. While water is used in the conventional extraction of resources, more water is used in conversion to useful forms of energy, whether that is converting coal or uranium to electricity as described above or converting petroleum into fuels such as gasoline or diesel. Refinery use of water for processing and cooling is about 1 to 2.5 gallons of water for every gallon of product (Gleick, 1994). The United States refines nearly 800 million gallons of petroleum products per day (EIA, 2006). Therefore, refining consumes 1 to 2 billion gallons of water per day. Natural gas processing and pipeline operations consume an additional 0.4 billion gallons per day (Gleick, 1994; EIA, 2006). In the mining sector, water is used to cool or lubricate cutting and drilling equipment for dust suppression, fuel processing, and revegetation when mining and extraction are complete. Estimates of water for coal mining vary from 1 to 6 gallons per million British thermal units (MMBtu), depending on the source of the coal (Gleick, 1994; Lancet, 1993). Combining those figures with 2003 coal production data (EIA, 2006), total water use for coal mining is estimated at 70 to 260 million gallons per day. Oil shale is emerging as another potential source of oil. Initial recovery work to date has focused on mining and above-ground processing (retorting) that consumes 2 to 5 gallons of water per gallon of refinery-ready oil (Bartis, 2005). Currently, only limited amounts of oil shale are being developed, but based on current oil demands and prices, opportunities may exist for significant expansion in the future. On the other hand, because oil shale resources are predominantly located in areas where water has a high value, oil shale development may be constrained by both water availability and value. More recently, an electrically driven in situ underground process is being prototyped that does not directly use water, potentially significantly reducing the water intensity of future oil shale development (Bartis, 2005). Biofuels currently provide about 3 percent of U.S. transportation fuel, with more than 130 ethanol and biodiesel plants in operation producing over 4 billion gallons of biofuel each year (Renewable Fuels Association, 20 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 20
2005 and 2006; National Biodiesel Board, 2005). The most water-intensive aspect of biofuel production is growing the feedstock, with water consumption for refining generally similar to that for oil refining. When the feedstock is corn or soy (used to make ethanol and biodiesel, respectively) and grown on irrigated land, then the water consumption per gallon of fuel produced can exceed the water consumption for refining by a factor of one thousand based on USDA data (USDA, 2004a). Initial extraction of conventional oil and gas requires minimal consumption of water. Rather, significant quantities of water, called produced water, are extracted with the oil and gas. Produced water can range from being nearly fresh to being hypersaline brine, with the vast majority being at least as saline as seawater. As oil wells age, enhanced recovery techniques are used to extract additional oil. Many of these recovery techniques involve injection of water or steam into the well, and some are very water-intensive. Gleick reports water consumption of 2 to 350 gallons of water per gallon of oil extracted, depending upon the recovery enhancement process. However, most of the water used for these purposes is not otherwise usable (Gleick, 1994). Most produced water associated with onshore production is injected back into the producing zones to enhance production or into other formations well below any usable groundwater resources. WATER PRODUCED DURING ENERGY EXTRACTION Significant quantities of produced water are extracted with oil and gas, as shown in Figure II-6. In 1995, the American Petroleum Institute (API) estimated that oil and gas operations generated 18 billion barrels of produced water (49 million gallons per day), compared to total annual petroleum production of 6.7 billion barrels of oil equivalent (both onshore and offshore production, including crude oil, natural gas, and natural gas liquids production) (API, 2000). Such produced water varies in quality; with treatment, some might be used for other purposes. API indicates that in 1995, approximately 71 percent of produced water was recycled and used for EOR. The amount of water produced per well varies greatly. For example, water produced by coal-bed natural gas extraction can vary from 7 barrels of water per barrel of oil equivalent in the San Juan Basin (Colorado and New Mexico) to approximately 900 barrels of water per barrel of oil equivalent in the Powder River Basin (Wyoming and Montana) (Rice et al., 2000). Additionally, produced water rates for coal-bed natural gas wells are not consistent over the life of the wells. Water production rates are high initially but decline rapidly. ENERGY IMPACTS ON WATER QUALITY As noted in Table II-1, many of the elements associated with energy development have the potential to impact water quality negatively. Oil and gas production that is not adequately managed and monitored can contaminate surface water and shallow groundwater through drilling and production operations or from spills of produced hydrocarbons or produced brackish water. The refining and processing of oil and gas can generate by-products and wastewater streams that, if not handled appropriately, can cause water contamination. Fuel additives, such as methyl tertiary-butyl ether (MTBE), that have been used to reduce air emissions have also emerged as potential groundwater contaminants. 21 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 21
Produced Water Forecast (MMbbls) by Resource Type Lower 48 States Onshore 25000 20000 15000 10000 Wp Total Wp Conventional Oil Wp Conventional Gas 5000 Wp Unconv Gas (e.g. Coal Bed Methane) 0 2004 2008 2012 2016 2020 2024 Figure II-6. Forecast for Produced Water (W p ) from Oil and Gas Extraction (Feeley et al., 2005) 22 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 22
Energy resource mining and processing, such as coal and uranium mining and oil shale development, can contaminate surface and groundwater. Runoff from both main mine operations and tailings piles can significantly reduce ph levels and increase heavy metals concentrations in mine drainage water. In addition, runoff from oil shale residue can wash into surface waters and byproducts from in situ retort methods could impact groundwater quality. An increased interest in U.S. uranium supplies has led some older mines in New Mexico and Utah to considering reopening. By doing so, these mines might generate from 3 to 5 million gallons of water a day that would need to be handled and disposed of (Hopp, 2005). On occasion, water is spilled from mining operations; 300 million gallons of coal sludge spilled in an incident in Kentucky in October 2000 (Clean Air Task Force, 2004a). Water from some abandoned mines, including some in Pennsylvania, must be pumped and treated to prevent contamination of surface waters (USGS, 2002a). Energy transportation and storage development can also impact surface water and groundwater quality. Water used for pipeline testing, coal slurry pipelines, and solution mining for oil and gas storage caverns creates a range of contaminants that can contaminate fresh or coastal water sources if not adequately managed and disposed of. Finally, thermoelectric and hydroelectric power generation can impact water quality. Discharge from open-loop cooling systems can affect water temperature and oxygen levels. Air emissions from fuel combustion, such as mercury, sulfur, and nitrogen oxides, can lead to negative impacts on downwind water quality and aquatic ecosystems. Hydroelectric plants can impact water quality and river ecology in several ways. Operations can change water temperatures and dissolved oxygen and nitrogen levels in downstream waters. Operations can also change the natural flow characteristics of rivers so as to impact aquatic ecology. 23 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 23
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Chapter III. Supplying Water Requires Energy Satisfying the Nation s water needs requires energy for supply, purification, distribution, and treatment of water and wastewater. Nationwide, about 4 percent of U.S. power generation is used for water supply and treatment, which, as shown in Figure III-1, is comparable to several other industrial sectors (EPRI, 2002b). Electricity represents approximately 75 percent of the cost of municipal water processing and distribution (Powicki, 2002). A recent study funded by the Electric Power Research Institute (EPRI) looked at energy requirements for water supply and treatment across the country. The results are examined in terms of per capita use of energy for water supply and treatment in Figure III-2. The biggest difference among regions is the amount of energy used to supply water for agriculture. In general, per capita non-agricultural use of energy for water is similar region to region. However, within regions, there can be substantial variation in energy requirements for water supply and treatment, depending upon the source, the distance water is conveyed, and the local topography. California is an % of US Electricty Consumption 7 6 5 4 3 2 1 0 Water/Wastewater Paper & Pulp Chemicals Petroleum Refining Figure III-1. Percent of U.S. Electricity Consumption by Sector (EPRI, 2002b; EIA, 1998) interesting case study in electrical consumption and illustrates the cost of long-distance water conveyance. California uses about 5 percent of its electricity consumption for water supply and treatment (CEC, 2005). This is substantially above the national average. As shown in Table III-1, a study by the California Energy Commission (CEC) illustrates how energy use can vary among water systems. SUPPLY AND CONVEYANCE Supply and conveyance can be the most energy-intensive portion of the water delivery chain. If the water source is groundwater, pumping requirements for supply of freshwater from aquifers vary with depth: 540 kwh per million gallons from a depth of 120 feet, 2000 kwh per million gallons from 400 feet (Cohen et al., 2004). These energy needs will increase in areas where groundwater levels are declining. Table III-1. Energy Requirements for Water Supply and Treatment in California (CEC, 2005) kwh/million gallons Water Cycle Segments Low High Supply and Conveyance 0 16,000 Treatment 100 1,500 Distribution 700 1,200 Wastewater Collection and Treatment 1,100 4,600 Wastewater Discharge 0 400 TOTAL 1,900 23,700 Recycled Water Treatment and Distribution for Nonpotable Uses 400 1,200 25 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 25
2000 2050 New England South Atlantic Middle Atlantic East North Central East South Central West North Central Public Water Supply Domestic Supply Commercial Supply Industrial Supply Mining Supply Public WW Treatment Private WW Treatment Livestock Irrigation Total U.S. Energy for Water Demand: 123 Million Mwh/yr New England South Atlantic Middle Atlantic East North Central East South Central West North Central Public Water Supply Domestic Supply Commercial Supply Industrial Supply Mining Supply Public WW Treatment Private WW Treatment Livestock Irrigation West South Central West South Central Mountain Mountain Pacific Pacific 0 200 400 600 800 1000 kwh/yr 0 200 400 600 800 1000 kwh/yr Figure III-2. Per Capita Energy Use for Water Supply and Wastewater Treatment in 2000 and Projected for 2050 (EPRI, 2002b). Energy requirements to pump water from surface waters can be negligible if users are located close to the source. But if water must be pumped long distances, then the energy requirement is much higher. In California, water is conveyed from Northern California up to 400 miles via the State Water Project to the cities of Southern California. Energy requirements for long-distance conveyance are indicated by the upper range in Table III-1. The table also illustrates that energy savings can be realized when wastewater streams are made available for reuse, rather than having to pump and convey freshwater over long distances. TREATMENT AND DISTRIBUTION Groundwater, if not brackish, can require minimal energy for purification. Surface waters generally require more treatment, and energy requirements for surface water treatment are at the upper end of the range in Table III-1. Energy requirements for distribution and collection vary depending on system size, topography, and age. Older systems often require more energy because of older infrastructure and less efficient equipment. END USE OF WATER One of the more interesting results that the California study noted is that energy consumption associated with using water is greater than the energy consumption for supply and treatment. Activities such as water heating, clothes washing, and clothes drying require 14 percent of California s electricity consumption and 31 percent of its natural gas consumption. Most of that use is in the residential sector. These data 26 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 26
illustrate that both water and energy can be conserved through the use of appliances and fixtures that reduce hot water use. FUTURE ENERGY DEMAND FOR WATER SUPPLY AND TREATMENT Population growth will create an increased demand for water. As freshwater supplies become more limited, pumping water from greater distances or greater depths and treating water to access alternative sources will increase energy consumption to meet future water demands. Additionally, emerging water treatment requirements (e.g., standards for arsenic removal) are becoming more stringent, which will increase energy consumption for both purification and wastewater treatment. In agriculture, gravity-driven flood irrigation may be replaced with more water-efficient but more energy-intensive spray irrigation and micro-irrigation. An increased demand for water and water treatment could provide incentives to improve the efficiency of the water infrastructure. Aging supply, treatment, and distribution equipment may be replaced by newer, more energy-efficient equipment, and water conservation measures, including improved irrigation practices, could reduce water use. The EPRI study estimated future energy demands for water supply and treatment in 2050. The results are presented on a per capita basis in Figure III-2. Compared to 2000, per capita energy requirements are expected to be largely unchanged, except in the industrial and agricultural sectors. Energy for public and commercial water supply and treatment are expected to grow with population, with an average increase for the Nation of almost 50 percent between 2000 and 2050. According to the EPRI study, energy use for water supply and treatment in the industrial sector is expected to triple because of growth projected in industrial activity, with strong growth in per capita use in the East North Central region. The study also projects that energy use for irrigation will triple based on projections of land use, with strong growth in per capita use in the South Central, West North Central, and West South Central regions. The study cites EPRI projections on industrial activity and U.S. Department of Agriculture (USDA) projections on land use (EPRI, 2002b). 27 CA Water Plan Update 2009 Vol. 4 Reference Guide Page 27